Multiple-optical-axis photoelectric switch, mounting structure therefor, and fixture therefor

ABSTRACT

A mounting structure for a multiple-optical-axis photoelectric switch comprising, a protrusion of a first member attached to cap members located on either end of the main case of one or both of a light receiving body and a light emitting body. The protrusion is interposed between a convex curved surface of a second member and a concave curved surface of a third member. Elongated holes in the protrusion allow the bodies to pivot about an axis containing the light emitters and light receivers. Consequently, a multiple-optical-axis photoelectric switch, mounting structure and fixture can be provided in which the optical axis can be adjusted without being influenced by the limitation in the spaces above and below the main case while the multiple-optical-axis photoelectric switch is mounted at a predetermined mounting part.

TECHNICAL FIELD

The present invention relates to multiple-optical-axis photoelectricswitch, and more particularly to a mounting structure for a main case ofa light emitter or light receiver of the multiple-optical-axisphotoelectric switch.

BACKGROUND ART

Multiple-optical-axis photoelectric switches comprise a light emitterhaving a plurality of light emitting elements aligned and a lightreceiver having a plurality of light receiving elements aligned andpaired with the light emitting elements respectively. Typically bothunits are disposed opposite to each other with a predetermined detectingregion interposed therebetween. When an object is present between thelight emitter and receiver, light emitted by the light emitter andtraveling toward the light receiver is intercepted by the object. As aresult, the amount of light received by the light receiver is reduced ascompared with the case where no object is present. Accordingly, anobject passing through the detecting region can be detected by measuringthe amount of light received by the light receiver.

Main cases for the respective light emitter and receiver in this type ofmultiple-optical-axis photoelectric switch are disclosed inJP-10-74433-A (hereinafter referred to as “document 1”) andJP-U-2554755-B (hereinafter referred to as “document 2”). As disclosed,each main case is mounted to a mounting wall by a pair of mountingplates provided on both ends thereof and having an L-shaped crosssection so as to pivot about a pivot shaft extending along the directionof alignment of the elements. Consequently, while each main case ismounted on the mounting wall, an optical axis can be adjusted so thatthe light emitted by each light emitter is received by the correspondinglight receiver.

The mounting structure will be explained concretely with the structureof the document 1 exemplified. The aforesaid L-shaped mounting plateincludes one of walls of the L-shaped mounting plate disposed oppositean end face of the main case, identified as the end face wall. The endface wall of the mounting plate is formed with an insertion hole and anarc groove having the insertion hole as its center, both extendingthrough the end face wall. The other wall of the mounting plate isdisposed opposite the mounting wall and is formed with a pair of throughholes through which fixing screws are inserted to be threadingly engagedwith the mounting wall. Mounting screws are inserted from an upper faceof the end face wall, through the insertion hole and the groove, to bethreadingly engaged with screw holes formed in the end of the main caserespectively. Fixing screws are inserted through the paired insertionholes of the other wall and are threadingly engaged with screw holes ofthe mounting wall respectively, whereby the main case is fixed to thefixing wall. In the adjustment of optical axis, the mounting screwinserted through the groove of the end face wall is loosened such thatthe main case is capable of pivoting about the insertion hole. Uponcompletion of the optical axis adjustment, the mounting screw isretightened so that the position of the optical axis is fixed.

The multiple-optical-axis photoelectric switch is installed in variousmounting places. There is sometimes a case where a sufficient spacecannot be ensured above or below the main case. In this case, theloosening and tightening of the mounting screws provided on the end ofthe main case with a suitable tool are difficult during the optical axisadjustment of the aforesaid documents 1 and 2. As a result, there can bea case where the fixing screws are detached so that the main case isdetached from the mounting wall in order to adjust the optical axis.

The present invention was made in view of the foregoing and an objectthereof is to provide a multiple-optical-axis photoelectric switch inwhich the optical axis can be adjusted without being influenced by thelimitation in the spaces above and below the main case when themultiple-optical-axis photoelectric switch is mounted at a predeterminedmounting part.

SUMMARY OF THE INVENTION

To achieve the object, a mounting structure for a multiple-optical-axisphotoelectric switch is described according to one aspect of the currentinvention. The switch includes a light emitter having a plurality oflight emitting elements aligned in a row and a light receiver having aplurality of light receiving elements paired with the light emittingelements respectively and also aligned in a row. At least one of thelight emitter and receiver includes a main case which is mounted at apredetermined mounting part so as to pivot about a pivot axis extendingalong a direction of alignment of the elements. The mounting structureis characterized by a first member provided on an end of the main casein the direction of alignment and having a protrusion extending in thedirection of alignment and having an arc cross section, a second memberhaving a convex curved surface with the same curvature as a concavecurved surface of the protrusion, a third member having a concave curvedsurface with the same curvature as a convex curved surface of theprotrusion, and a mounting screw. Wherein the protrusion of the firstmember is interposed between the convex curved surface of the secondmember and the concave curved surface of the third member. Either one ofthe second and third members is formed with a screw insertion holeextending therethrough from the curved surface opposed to the protrusionto an outer surface opposite the curved surface. The other of the secondand third members is provided with a fixing section adapted to be fixedto the mounting part and a screw hole formed in the curved surfaceopposed to the protrusion so that the mounting screw, having beeninserted through the screw insertion hole from the outer surface of saidone member, is threadingly engaged with the screw hole. The protrusionhas a guiding elongated hole located between the screw insertion holeand the screw hole and extending in the direction of the periphery ofthe protrusion. The elongated hole having a larger width than a diameterof the mounting screw.

Another aspect of the current invention is characterized by thefollowing. The mounting structure for the multiple-optical-axisphotoelectric switch, according to the previous aspect of the currentinvention, is modified so that the second member, having the convexcurved surface, is formed to be recessed at a side opposite to theconvex curved surface. The recess is formed so that the second memberaccommodates a signal cable drawn from the end of the main case.

Another aspect of the current invention is characterized by thefollowing. The mounting structure for the multiple-optical-axisphotoelectric switch, according to any of the previous aspects of thecurrent invention, is modified so that the second member is formed withthe screw insertion hole and the third member is formed with the fixingsection and the screw hole. The protrusion is formed so as to have as acenter thereof an axis, extending in the direction of alignment, on afront surface of the main case toward which each element is directed.The protrusion is formed so as to have an arc cross section.

A fixture for a multiple-optical-axis photoelectric switch is describedaccording to yet another aspect of the current invention. The switchincludes a light emitter having a plurality of light emitting elementsaligned in a row and a light receiver having a plurality of lightreceiving elements paired with the light emitting elements respectivelyand aligned in a row. At least one of the light emitter and receiverincludes a main case which is mounted at a predetermined mounting partby the mounting structure as defined in any one of the preceding aspectsof the current invention. The fixture being used to mount said main caseprovided with the first member at the predetermined mounting part sothat said main case is capable of pivoting about a pivot axis extendingalong a direction of alignment of the elements. The fixture ischaracterized in that the fixture is provided with the second and thirdmembers and the mounting screw.

A fixture for a multiple-optical-axis photoelectric switch is describedaccording to still another aspect of the current invention. The switchincludes a light emitter having a plurality of light emitting elementsaligned in a row and a light receiver having a plurality of lightreceiving elements paired with the light emitting elements respectivelyand aligned in a row. At least one of the light emitter and receiverincludes a main case which is mounted at a predetermined mounting partby the mounting structure as defined in any one of the first threeaspects of the current invention. The fixture is used to mount said maincase at the predetermined mounting part so that said main case iscapable of pivoting about a pivot axis extending along a direction ofalignment of the elements. The fixture is characterized in that thefixture is provided with the first, second, and third members, and themounting screw.

A multiple-optical-axis photoelectric switch is described according toyet still another aspect of the current invention. The switch includes alight emitter having a plurality of light emitting elements aligned in arow and a light receiver having a plurality of light receiving elementspaired with the light emitting elements respectively and aligned in arow. At least one of the light emitter and receiver includes a main casewhich is mounted at a predetermined mounting part by the mountingstructure as defined in any one of the first three aspects of thecurrent invention. The switch is characterized by a fixture providedthereon. The first member is provided at the main case side and thefixture is provided with the second and third members and the mountingscrew.

A multiple-optical-axis photoelectric switch according to a furtheraspect of the current invention is described as follows. The switchincludes a light emitter having a plurality of light emitting elementsaligned in a row and a light receiver having a plurality of lightreceiving elements paired with the light emitting elements respectivelyand aligned in a row. At least one of the light emitter and receiverincludes a main case which is mounted at a predetermined mounting partby the mounting structure as defined in any one of the first threeaspects of the current invention. The switch is characterized by afixture provided thereon. The fixture is provided with the first,second, and third members, and the mounting screw.

According to the mounting structure of the first aspect of the currentinvention, the protrusion of the first member provided on the end of themain case is interposed between the convex curved surface of the secondmember and the concave curved surface of the third member. The firstaspect of the current invention includes, for example, the followingconstructions (a) and (b):

(a) The construction in which the second member is formed with the screwinsertion hole and the third member is formed with the fixing section(the second member is “one member” and the third member is “the othermember”).

In this construction, the mounting screw, having been inserted throughthe screw insertion hole formed in the second member and the guidingelongated hole of the protrusion, is threadingly engaged with the screwhole formed in the concave curved surface of the third member. Thefixing portion of the third member is secured to the mounting part.

(b) The construction in which the second member is formed with thefixing portion and the screw hole, and the third member is formed withthe screw insertion hole (the second member is “the other member” andthe third member is “one member”).

In this construction, the mounting screw, having been inserted throughthe screw insertion hole formed in the third member and the guidingelongated hole of the protrusion, is threadingly engaged with the screwhole formed in the convex curved surface of the second member. Thefixing portion of the second member is secured to the mounting part.

Consequently, the main case can be mounted on the mounting part. Whenthe adjustment of the optical axis is required, the mounting screw,inserted through the screw insertion hole and the guiding elongatedhole, is loosened. The mounting screw is in threading engagement with anouter surface of the second member directed sideways (perpendicular)relative to the direction of alignment of the elements (the surfaceopposed the convex curved surface) in the construction (a). In theconstruction (b), the mounting screw is in threading engagement with anouter surface of the third member directed sideways (perpendicular)relative to the direction of alignment of the elements (the surfaceopposed the concave curved surface).

According to the construction, a predetermined tool is applied to themounting screw at the side of the main case in order for the mountingscrew to be loosened or tightened for the optical axis adjustment.Accordingly, even when the space defined above or below the main case isnarrow, the mounting screw can be loosened or tightened for the opticalaxis adjustment while the main case is mounted on the mounting part.

Further, there is the construction in which a signal cable is drawn outfrom the end of the main case. According to the mounting structure ofthe second aspect of the current invention, the second member is formedso as to be recessed (for example, with a groove) at the outer surfaceside (the surface opposed to the convex curved surface) so that thesecond member bypasses the signal cable. Accordingly, when the main caseis caused to pivot, an outer periphery of the signal cable can beprevented as much as possible from being damaged by, for example,sliding contact of the second member.

Further, according to the mounting structure of the third aspect of thecurrent invention, in the construction (a), the protrusion is formed soas to have as a center thereof an axis, extending in the direction ofalignment, on a front surface of the main case toward which each elementis directed. The protrusion is formed so as to have an arc crosssection. More specifically, the main case pivots about a line on thefront surface thereof (a light emitting surface of the light emitter anda light receiving surface of the light receiver). Accordingly, in thecase of the light emitter, only the light-emitting direction (thedirection of the optical axis) can be changed without changing thelocation of light emission from each light emitting element. In the caseof the light receiver, only the light-receiving direction (the directionof the optical axis) can be changed without changing the location whereeach light receiving element can receive light. Accordingly, the opticalaxis can easily be adjusted even when the light emitted by the lightemitter has a relatively small width or even when the light-receivingarea at the light receiver side is narrow.

Although differing from the construction of the present invention,another construction can be considered which comprises a pivot shaftprotruding from an end of a cap fitted onto an open end of the maincase. A first member is fixed to the mounting part and a second memberhas a groove covering an outer periphery of the pivot shaft from oneside. The first and second members are secured to each other at sideportions of the grooves by a mounting screw inserted through the outersurface of the first member. This construction can achieve substantiallythe same effects as achieved by the above-described present invention.

However, when the signal cable is drawn out of the lengthwise end of themain case in the construction provided with a pivot shaft, it should beconsidered that the signal cable is drawn out through the cylindricallyshaped pivot shaft. Accordingly, when the aforesaid cap member isattached to the open end of the main case, the signal cable is firstinserted through the pivot shaft of the cap member. At this point theassembly work of the multiple-optical-axis photoelectric switch becomestroublesome. A connector having a larger diameter than the cable wire isusually provided on a distal end of the signal cable. In order that theconnector may be insertable, the size of the pivot shaft must beincreased. Subsequently the whole fixture is rendered large in size andaccordingly, this is not a desirable construction.

On the other hand, the mounting structure of the present invention doesnot surround the whole periphery of the signal cable. Accordingly, thefirst to third members can be assembled to one side of the signal cable(the right-and-left direction perpendicularly across the axis of thecable) with the signal cable being a center. Consequently, the assemblywork is relatively easy and further; the fixture need not be renderedlarge in size in order to accommodate the diameter of the connector atthe distal end of the signal cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the multiple-optical-axis photoelectricswitch in accordance with a first representative embodiment of thepresent invention in a mounted state;

FIG. 2 is an exploded view of the light emitter;

FIG. 3 is an exploded perspective view of the fixture;

FIGS. 4(A) to 4(D) are a side view, top view, front view and rear viewof the first member;

FIGS. 5(A) and 5(B) are a top view and side view of the second member;

FIGS. 6(A) to 6(C) are a top view, side view and front view of the thirdmember;

FIG. 7 is a perspective view showing the assembled state of the fixture;

FIGS. 8(A) and 8(B) are partially sectional views showing a non-pivotedstate of the main case;

FIGS. 9(A) and 9(B) are partially sectional views showing a non-pivotedstate of the main case in a second representative embodiment; and

FIGS. 10(A) and 10(B) are partially sectional views showing anon-pivoted state of the main case in a modified form.

BEST MODE FOR CARRYING OUT THE INVENTION

<First Representative Embodiment>

A first representative embodiment of the present invention will bedescribed with reference to FIGS. 1 to 8.

1. Outline of Multiple-optical-axis Photoelectric Switch

The multiple-optical-axis photoelectric switch 10 of the embodimentincludes a light emitter 12 having a plurality of light emittingelements 11 aligned in a row and a light receiver 13 having a pluralityof light receiving elements (not shown) paired with the light emittingelements 11 respectively and aligned in a row. The units are disposedopposite to each other with a predetermined detecting region beingdefined therebetween, as shown in FIG. 1. When an object is presentbetween the light emitter 12 and light receiver 13, the light emitted bythe light emitter 12 and traveling toward the light receiver 13 isintercepted (blocked) by the object. As a result, the amount of lightreceived by the light receiver 13 is reduced as compared with the casewhere no object is present. Accordingly, an object passing through thedetecting region can be detected by measuring the amount of lightreceived by the light receiver 13. Main cases 14 of the light emitter 12and light receiver 13, are mounted by fixtures 20, having a structurewhich will be described later, on a pair of opposed walls W at adetecting part E with a rectangular opening (corresponding to “apredetermined mounting part”). The main cases 14 pivot about a pivotaxis extending along the direction of alignment of the elements 11(vertically as viewed in FIG. 1).

These structures will be described in detail with the light emitter 12side being exemplified. In the following description, the direction inwhich the elements of the light emitter 12 and light receiver 13 aredirected will be referred to as a frontward direction, whereas theopposed wall W side will be referred to as a rear.

2. Concrete Construction

(1) Light Emitter:

The light emitter 12 comprises a light emitting unit 15 enclosing, forexample, eight light emitting elements 11 aligned in a row. Lightemitter 12 also comprises a main case 14, which has a generally C-shapedcross section and in which the light emitting unit 15 is housed, asshown in FIG. 2. More specifically, the light emitting unit 15 includesa housing case 16. Housing case 16 is formed with a cylindricallight-emitting window 16A containing an opening which is formed in oneside thereof and closed by a light-transmitting member. The eight lightemitting elements 11 are housed in the housing case 16 so as to bealigned in a row corresponding with the light-emitting window 16A.Furthermore, a pair of box-shaped cap members, 17A and 17B, arerespectively fitted in the open ends of the main case 14. In theembodiment, one cap member 17B (attached to the lower side in FIGS. 1and 2) has a proximal end electrically connected to the inner circuit ofthe light emitting unit 15 at the side of light emitting unit 15directly opposed to the side of 17B to which the main case 14 isattached. The cap member 17B further has a distal end from which asignal cable 18, to which a connector 18A is attached, is drawn out. Aplurality of display lamps 16B are juxtaposed on the lower end of thelight emitting unit 15. The display lamps 16B include an optical axisalignment display lamp, actuated according to the optical axisalignment, an operation display lamp, actuated according to the controlof the light emission, a failure display lamp, and the like.

(2) Mounting Structure of Fixture:

The fixture 20 has a structure corresponding to structure (a) describedpreviously in the Summary section of the present invention. Morespecifically, the fixture 20 includes a first member 22 having aprotrusion 21 with an arc cross section, a second member 25 formed withscrew insertion holes, a third member 30 formed with a fixing sectionand screw holes, and a pair of mounting screws 35.

(A) First Member:

The first member 22 is attached to the side of the cap member 17A (17B)opposite to the main case 14. The first member 22 includes a U-shapedportion 23 which has a substantially U-shaped cross section andpartially surrounds the outer peripheral surface of the signal cable 18drawn from the cap member attached to the side of first member 22. Firstmember 22 also has a protrusion 21 which extends along the end surfaceopposite to the side of the U-shaped portion 23 attached to the capmember 17A (17B), and also partially surrounds the signal cable 18. TheU-shaped portion 23 has a pair of through holes 23A extending throughboth upper ends of the U in the direction of alignment. A pair of screws24 are inserted through the holes 23A to be threadingly engaged with apair of screw holes 19A, formed in cap members 17A and 17B, whereby theU-shaped portion 23 is secured to the cap member 17A (17B). Three setsof protruding and recessed portions, 19B and 23B (see FIGS. 4(A) to4(D)), are formed in opposed sides of the cap member 17A (17B) and theU-shaped portion 23, so that the first member 22 is positioned and fixedto the cap members 17A and 17B.

The aforesaid protrusion 21 is formed so as to have an arc cross sectionwith the signal cable 18 attached to the cap member 17A (17B) serving asthe center thereof (corresponding to “a pivot axis” in the presentinvention). See FIGS. 8(A) and 8(B). The protrusion 21 further has apair of guiding elongated holes 21A, each of which has a larger widththan the diameter of the mounting screws 35. The guiding elongated holes21A extend circumferentially with respect to the protrusion 21. Thefirst member 22 is not required to have a U-shaped cross section for thefixture 20 attached to the cap member 17A side from which no signalcable 18 is drawn out (the cap member at the upper end side of the lightemitter 12 in FIGS. 1 and 2). The first member 22 may be constructed sothat the protrusion 21 extends from one end surface side of a box-shapedmember.

(B) Second Member:

The second member 25 is disposed at the inner curved surface 21B(corresponding to “a concave curved surface of the protrusion”, thefront side) of the protrusion 21 of the first member 22. The secondmember 25 is formed so as to have a substantially semicircular crosssection and has an outer curved surface constituting “a convex curvedsurface” in the invention (hereinafter, referred to as “convex curvedsurface 25A”), as shown in FIGS. 5(A) and 5(B). The convex curvedsurface 25A has substantially the same curvature as the inner curvedsurface 21B of the protrusion 21. Further, the second member 25 has apair of screw insertion holes 26 which are formed in both ends of theflat surface 25B, opposite to the convex curved surface 25A, so as toextend in parallel to each other through the convex curved surface 25A.The second member 25 may further have a groove 27 which is formed in aportion thereof between the screw insertion holes 26 on the flat surface25B. The groove 27 may be recessed to have a curved surface parallel tothe convex curved surface 25A. The signal cable 18 can extend throughthe groove 27. The fixture 20 attached to the cap member 17A (the capmember at the upper end side of the light emitter 12 in FIGS. 1 and 2),from which the signal cable 18 is not drawn, may be formed with nogroove 27.

(C) Third Member:

The third member 30 (see FIGS. 6(A) to 6(C) is disposed on a protrudingouter curved surface 21C (corresponding to “a convex curved surface ofthe protrusion”, the rear side) of the protrusion 21 of the first member22 and fixed to opposed wall W. More specifically, the third member 30has a rectangular flat portion 31 mounted on opposed wall W and aupright wall rising from one edge of the flat portion 31. Both walls ofthird member 30 are formed integrally with each other and result in asubstantially L-shaped cross section. The upper side of the upright wallserves as a concave curved surface 32A, recessed into the general shapeof a suspension bridge. The curved surface 32A has the same curvature asthe outer curved surface 21C of the protrusion 21. The concave curvedsurface 32A has a pair of screw holes 33 which are formed so as to bedirectly opposed to the pair of screw holes 26 of the second member 25.The mounting screws 35 are threadingly engaged with the screw holes 33.

The flat portion 31 is formed with a pair of through holes 31A. A pairof fixing screws 34 (see FIG. 1) are inserted through the holes 31A tobe threadingly engaged with screw holes (not shown) formed in theopposed wall W, whereby the third member 30 is secured to the opposedwall W. The aforesaid pair of through holes 31A are formed intoelongated slots extending lengthwise with respect to the light emitter12 (vertically as shown in FIG. 1), whereupon the third member 30 can bemounted on the opposed wall W and be finely adjusted vertically.

In the above-described construction, the first member 22 is attached tothe cap members 17A and 17B by the pair of screws 24, and the secondmember 25 is disposed between the signal cable 18 and the inner curvedsurface 21B of the protrusion 21, as shown in FIG. 3 and FIG. 7.Further, the concave curved surface 32A of the third member 30 is incontact with the outer curved surface 21C of the protrusion 21 from therear. Subsequently, the mounting screws 35 are inserted through thescrew insertion holes 26 of the second member 25 and the elongated holes21A of the protrusion 21 and then threadingly engaged with the screwholes 33. Whereby the protrusion 21 is held between the second member 25and the third member 30 so as to be fixed in position. The third member30 is then mounted on the opposed wall W so that the light emitter 12 iscorrespondingly mounted on the opposed wall W.

When the direction of light (light axis) emitted from the light emittingelements 11 of the light emitter 12 mounted on the opposed wall W is tobe adjusted, the mounting screws 35, mounted on the flat portion 25B ofthe frontwards directed second member 25, are loosened using apredetermined tool, so that the light emitter 12 can pivot about thesignal cable 18 by an angle limited by the length of the elongated holes21A of the protrusion 21. When an angle is reached such that lightemitted from each light emitting element 11 is received by the lightreceiving element 13 paired with each respective light emitting element11, the mounting screws 35 are re-tightened so that the light emitter 12is fixed in position.

The light receiver 13 has the same structure as the foregoing lightemitter 12 and may be mounted on the opposite opposed wall W so as topivot. Whereupon the light emitter 12 and the light receiver 13 canpivot so that the optical axis of each light emitting element 11corresponds with the optical axis of each light receiving element of thelight receiver 13. Consequently, the direction of the optical axis canbe readily adjusted.

3. Effect of the Embodiment

According to the mounting structure of the embodiment, the pair ofmounting screws 35, mounted on the flat surface of the frontwardsdirected second member 25, are loosened using the predetermined tool, sothat the light emitter 12 or the light receiver 13 is allowed to pivotfor the adjustment of the optical axis (as seen in FIGS. 8(A) and 8(B).Accordingly, even when the spaces defined above and below the lightemitter 12 and the light receiver 13 are narrow, the mounting screws 35can be loosened and tightened for the adjustment of the optical axiswhile the light emitter and light receiver remain mounted on the opposedwalls W.

Further, since the second member 25 may be formed with a groove so as tobypass the signal cable 18, the outer periphery of the signal cable 18can be prevented as much as possible from being damaged by, for example,sliding contact of the second member 25 when the main case 14 ispivoted.

<Second Representative Embodiment>

FIGS. 9(A) and 9(B) illustrate a second representative embodiment(corresponding to the invention of previously described embodiment 3).The second representative embodiment differs from the previousembodiment in the protrusion of the first member and the curvature ofthe convex and concave curved surfaces of the second and third members.The second representative embodiment is the same as the firstrepresentative embodiment in most other respects. Accordingly, theidentical or similar parts are labeled in the second representativeembodiment by the same reference symbols as those in the firstrepresentative embodiment. Repeated descriptions are eliminated and onlythe differences will be described.

As shown in FIG. 9(A), the protrusion 40 is formed so as to have an arccross section with an axis X serving as the center thereof. The axis Xextends in the direction of alignment of the light emitting elements 11and the like, along the front surface of the light emitter 12 formedwith the light emitting window 16A. The convex curved surface 41A of thesecond member 41 has the same general curvature as the inner curvedsurface 40B (corresponding to “a concave curved surface” in theinvention) of the protrusion 40. The concave curved surface 42A of thethird member 42 has the same general curvature as the outer curvedsurface 40C (corresponding to “a convex curved surface of theprotrusion” in the invention) of the protrusion 40.

Accordingly, the main case 14 pivots about the axis X located on thefront surface (also the front surface formed with the light receivingwindow in the light receiver 13) of the light emitter 12 formed with thelight emitting window 16A, as shown in FIG. 9(B). Accordingly, in thecase of the light emitter 12, only the light-emitting direction (thedirection of optical axis) can be changed without changing the locationof the light emission from each light emitting element 11 relative tothe light emitting window 16A. In the case of the light receiver 13,only the light-receiving direction (the direction of optical axis) canbe changed without changing the location where each light receivingelement can receive light (relative to the light receiving window).Accordingly, the optical axis can easily be adjusted even when the lightemitted by the light emitter 12 has a small width or even when thelight-receiving area at the light receiver 13 side is narrow.

<Other Representative Embodiments>

The invention should not be limited by the foregoing representativeembodiments. For example, the representative embodiments which will bedescribed as follows are contained within the technical scope of theinvention. Further, the invention may be modified without departing fromthe subject matter of the invention in ways other than the following.

(1) The construction corresponding to the construction (a) in theSummary section of the invention is employed in the foregoingembodiments. However, the construction corresponding to the construction(b) may be employed, instead. FIGS. 10(A) and 10(B) illustrates aconcrete construction. The second member 50 is formed with a fixingsection 51 and screw holes 52, and the third member 53 is provided withscrew insertion holes 54. This construction can achieve the same effectas was achieved from the foregoing first representative embodiment.

(2) In the foregoing representative embodiments, the guiding elongatedholes formed in the protrusion 21 may instead be notches formed bycutting the end of protrusion 21. A pair of mounting screws may beinserted through the notches for example.

(3) Two mounting screws are provided in the foregoing representativeembodiments. One, three, or more, mounting screws may be providedinstead.

(4) The first and second representative embodiments and the modifiedform as shown in FIGS. 10(A) and 10(B), are all applicable to the photoreceiver 13 side and accordingly, the same effect can be achieved.

(5) The protrusions 21 and 40 are provided on the first member 22,discrete from the light emitter 12 and the light receiver 13 (the capmembers 17A and 17B) in the foregoing representative embodiments.However, the protrusions may be provided directly on components of thelight emitter 12 and the light receiver 13 (for example, the cap members17A and 17B) respectively (corresponding to the construction of thepreviously described fourth and sixth embodiments). In this case, thecap members may serve as the first members.

INDUSTRIAL APPLICABILITY

The multiple-optical-axis photoelectric switch, mounting structure, andfixture, can be provided so that the optical axis can be adjustedwithout being influenced by the limitation in the spaces above and belowthe main case while the multiple-optical-axis photoelectric switch ismounted at a predetermined mounting part.

1. A mounting structure for a multiple-optical-axis photoelectric switchincluding a light emitter having a plurality of light emitting elementsaligned in a row and a light receiver having a plurality of lightreceiving elements corresponding to the light emitting elements andaligned in a row, at least one of the light emitter and the lightreceiver including a main case, the mounting structure adapted to fixthe case to a predetermined mounting part so as to allow the case topivot about a pivot axis extending along a direction of alignment of theelements, the mounting structure comprising: a first member attached toa longitudinal end of the main case and having a protrusion extending inthe direction of alignment and having an arc cross section comprising aconcave surface; and a convex surface; a second member; and a thirdmember; and a mounting device, wherein the protrusion of the firstmember is interposed between the second member and the third member;wherein one of the second member and the third member has a concavesurface to slidingly interface with the convex surface of the protrusionof the first member; and wherein the other of the second member and thethird member has a convex surface to slidingly interface with theconcave surface of the protrusion of the first member; and wherein oneof the second member and third member is formed with at least one screwinsertion hole extending therethrough; and wherein the other of thesecond member and the third member is formed with a fixing sectionadapted to be fixed to the mounting part and at least one screw holeadapted to be threadingly engaged with the mounting device; and whereinthe protrusion of the first member can be fixed in position bytightening the mounting device; and wherein the mounting device isoperated generally perpendicular to the pivot axis.
 2. The mountingstructure for the multiple-optical-axis photoelectric switch accordingto claim 1, wherein the protrusion of the first member furthercomprises: at least one guiding elongated hole adapted to slidinglyinterface with the mounting device.
 3. The mounting structure for themultiple-optical-axis photoelectric switch according to claim 1, whereinthe protrusion of the first member further comprises: at least one notchadapted to slidingly interface with the mounting device.
 4. The mountingstructure for the multiple-optical-axis photoelectric switch accordingto claim 1, further comprising: a recess formed in one of the secondmember and the third member and adapted to accommodate a signal cabledrawn from the end of the main case.
 5. The mounting structure for themultiple-optical-axis photoelectric switch according to claim 1,wherein: the second member is formed comprising the at least one screwinsertion hole; and the third member is formed comprising the fixingsection; and the at least one screw hole; and the protrusion is formedso as to have as a center thereof an axis extending in the direction ofalignment on a front surface of the main case toward which each elementis directed.
 6. A mounting structure for a multiple-optical-axisphotoelectric switch according to claim 1, wherein: the mounting deviceis a mounting screw.
 7. A fixture for a multiple-optical-axisphotoelectric switch including a light emitter having a plurality oflight emitting elements aligned in a row and a light receiver having aplurality of light receiving elements corresponding to the lightemitting elements and aligned in a row, at least one of the lightemitter and the light receiver including a main case with a first memberattached to a longitudinal end of the main case and having a protrusionextending in the direction of alignment comprising an arc cross section,a concave surface, and a convex surface; the fixture adapted to fix themultiple-optical-axis photoelectric switch to a predetermined mountingpart so that the multiple-optical-axis photoelectric switch is capableof pivoting about a pivot axis extending along a direction of alignmentof the elements, the fixture comprising: a second member; and a thirdmember; and a mounting device; wherein the protrusion of the firstmember is interposed between the second member and the third member;wherein one of the second member and the third member has a concavesurface to slidingly interface with the convex surface of the protrusionof the first member; and wherein the other of the second member and thethird member has a convex surface to slidingly interface with theconcave surface of the protrusion of the first member; and wherein oneof the second member and third member is formed with at least one screwinsertion hole extending therethrough; and wherein the other of thesecond member and the third member is formed with a fixing sectionadapted to be fixed to the mounting part and at least one screw holeadapted to be threadingly engaged with the mounting device; and whereinthe protrusion of the first member can be fixed in position bytightening the mounting device; and wherein the mounting device isoperated generally perpendicular to the pivot axis.
 8. The fixture forthe multiple-optical-axis photoelectric switch according to claim 7,wherein the protrusion of the first member further comprises: at leastone guiding elongated hole adapted to slidingly interface with themounting device.
 9. The fixture for the multiple-optical-axisphotoelectric switch according to claim 7, wherein the protrusion of thefirst member further comprises: at least one notch adapted to slidinglyinterface with the mounting device.
 10. The fixture for themultiple-optical-axis photoelectric switch according to claim 7, furthercomprising: a recess formed in one of the second member and the thirdmember and adapted to accommodate a signal cable drawn from the end ofthe main case.
 11. The fixture for the multiple-optical-axisphotoelectric switch according to claim 7, wherein: the second member isformed comprising the at least one screw insertion hole; and the thirdmember is formed comprising: the fixing section; and the at least onescrew hole; and the protrusion is formed so as to have as a centerthereof an axis extending in the direction of alignment on a frontsurface of the main case toward which each element is directed.
 12. Afixture for a multiple-optical-axis photoelectric switch according toclaim 7, wherein: the mounting device is a mounting screw.
 13. A fixturefor a multiple-optical-axis photoelectric switch including a lightemitter having a plurality of light emitting elements aligned in a rowand a light receiver having a plurality of light receiving elementscorresponding to the light emitting elements and aligned in a row, atleast one of the light emitter and the light receiver including a maincase, the fixture adapted to fix the multiple-optical-axis photoelectricswitch to a predetermined mounting part so that themultiple-optical-axis photoelectric switch is capable of pivoting abouta pivot axis extending along a direction of alignment of the elements,the fixture comprising: a first member adapted to be fixed to alongitudinal end of the main case and having a protrusion extending inthe direction of alignment comprising, an arc cross section, and aconcave surface, and a convex surface; a second member; and a thirdmember; and a mounting device; wherein the protrusion of the firstmember is interposed between the second member and the third member;wherein one of the second member and the third member has a concavesurface to slidingly interface with the convex surface of the protrusionof the first member; and wherein the other of the second member and thethird member has a convex surface to slidingly interface with theconcave surface of the protrusion of the first member; and wherein oneof the second member and third member is formed with at least one screwinsertion hole extending therethrough; and wherein the other of thesecond member and the third member is formed with a fixing sectionadapted to be fixed to the mounting part and at least one screw holeadapted to be threadingly engaged with the mounting device; and whereinthe protrusion of the first member can be fixed in position bytightening the mounting device; and wherein the mounting device isoperated generally perpendicular to the pivot axis.
 14. The fixture forthe multiple-optical-axis photoelectric switch according to claim 13,wherein the protrusion of the first member further comprises: at leastone guiding elongated hole adapted to slidingly interface with themounting device.
 15. The fixture for the multiple-optical-axisphotoelectric switch according to claim 13, wherein the protrusion ofthe first member further comprises: at least one notch adapted toslidingly interface with the mounting device.
 16. The fixture for themultiple-optical-axis photoelectric switch according to claim 13,further comprising: a recess formed in one of the second member and thethird member and adapted to accommodate a signal cable drawn from theend of the main case.
 17. The fixture for the multiple-optical-axisphotoelectric switch according to claim 13, wherein: the second memberis formed comprising the at least one screw insertion hole; and thethird member is formed comprising: the fixing section; and the at leastone screw hole; and the protrusion is formed so as to have as a centerthereof an axis extending in the direction of alignment on a frontsurface of the main case toward which each element is directed.
 18. Afixture for a multiple-optical-axis photoelectric switch according toclaim 17, wherein: the mounting device is a mounting screw.
 19. Amounting structure for a multiple-optical-axis photoelectric switchincluding a light emitter having at least one light emitting element anda light receiver having at least one light receiving elementscorresponding to the light emitting elements, at least one of the lightemitter and the light receiver including a main case, the mountingstructure adapted to fix the case to a predetermined mounting part so asto allow the case to pivot about a pivot axis extending along alongitudinal direction of the case, the mounting structure comprising: afirst member attached to a longitudinal end of the main case and havinga protrusion extending in the direction of alignment; a second memberadapted to slidingly engage the protrusion of the first member; and athird member adapted to slidingly engage the protrusion of the firstmember; and a mounting device, wherein the protrusion of the firstmember is interposed between the second member and the third member;wherein one of the second member and third member is formed with atleast one screw insertion hole extending therethrough; and wherein theother of the second member and the third member is formed with a fixingsection adapted to be fixed to the mounting part and at least one screwhole adapted to be threadingly engaged with the mounting device; andwherein the protrusion of the first member can be fixed in position bytightening the mounting device; and wherein the mounting device isoperated generally perpendicular to the pivot axis.
 20. A fixture for amultiple-optical-axis photoelectric switch including a light emitterhaving at least one light emitting element and a light receiver havingat least one light receiving element corresponding to the tight emittingelement, at least one of the light emitter and the light receiverincluding a main case, the fixture adapted to fix themultiple-optical-axis photoelectric switch to a predetermined mountingpart so that the multiple-optical-axis photoelectric switch is capableof pivoting about a pivot axis extending along a longitudinal directionof the multiple-optical-axis photoelectric switch, the fixturecomprising: a first member adapted to be fixed to a longitudinal end ofthe main case and having a protrusion extending in the direction ofalignment comprising, a second member adapted to slidingly engage theprotrusion of the first member; and a third member adapted to slidinglyengage the protrusion of the first member; and a mounting device;wherein the protrusion of the first member is interposed between thesecond member and the third member; wherein one of the second member andthird member is formed with at least one screw insertion hole extendingtherethrough; and wherein the other of the second member and the thirdmember is formed with a fixing section adapted to be fixed to themounting part and at least one screw hole adapted to be threadinglyengaged with the mounting device; and wherein the protrusion of thefirst member can be fixed in position by tightening the mounting device;and wherein the mounting device is operated generally perpendicular tothe pivot axis.